In a photoresist process, which is one of a semiconductor manufacturing process, a resist film is coated on a semiconductor wafer (hereinafter abbreviated as a “wafer”) serving as a substrate to expose and/or develop the wafer with a predetermined pattern, thereby forming a pattern of resist. The wafer is subjected to a heat treatment before and after the resist film is coated or before and after the resist film is developed.
In some cases, modules of a substrate processing apparatus perform processes for the wafer while generating a gas current on the surface of the wafer. For example, a heating module performs the heating process under a state where the gas current is generated on the wafer surface in order to prevent sublimates from being attached to the wafer, which may be derived from various films such as the resist film formed on the wafer. Additionally, in forming the resist film, a spin coating is also used to supply gas onto the wafer surface from above a cup-like component onto which the wafer is loaded, while exhausting the interior of the cup-like component, such that mists cannot be attached to the wafer.
However, if the direction and speed of the gas current generated in different portions of the planar surface of the wafer are in disorder, a distribution of temperature on the planar surface of the wafer is also in disorder, which may result in deterioration of process uniformity on the surface of the wafer. In addition, deviations may be possible in the direction and speed of gas currents between different modules which perform the same process for different wafers, which may result in deterioration of process uniformity between wafers. In order to prevent such deterioration of process uniformity, gas currents of module(s) has been adjusted by measuring the direction and speed of the gas currents through a simulation by a computer. However, due to circumstances that require higher process uniformity on a planar surface of a wafer and between wafers, there is a need for measuring a distribution of direction and speed of gas currents on the planar surface of the wafer with higher precision by a substrate processing module.
Currently, known module techniques that utilize sensors are insufficient for overcoming the above problems since they cannot measure the distribution of gas current directions and speeds on a wafer plane.